To a very significant degree, pharmaceutical substances are administered in the form of so-called pellets. In order to achieve a delayed emission of the effective substance, the pellet containing the substance is coated with a layer made of such a material that the gastric and intestinal juices release the substance from the pellet at a slow rate in accordance with diffusion principles. To a relevant degree, the pellet usually consists of pre-fabricated cores made of a material that dilutes in gastric and intestinal juices, for example with starch or similar sugar crystal compounds (saccharose crystals), upon which is the depository coating, which contains the medicament substance, and finally the outer coating, which causes the continuous, delayed medicament substance emission, are applied. Finally, very often another outer coating, also containing the medicament substance, is applied from which the medicament substance is absorbed immediately after the pellet has been administered and, thereby, an initial dosage of the substance is released to achieve a certain, desired medicament substance level in the circulatory system.
The task of this form of preparation is to provide continuous and delayed of medicament substance emission, while maintaining the desired blood absorption level over the entire determined period of time, and an essentially complete emission of substance from the product, if applicable, after achieving a desired initial substance level in the circulatory system of the patient for a predetermined period of time, e.g., for a number of hours.
The solution of this task for such types of pellets, however, is disturbed by the fact that the outer coating, which causes the continuous and delayed substance emission, perforates prematurely after the pellet has been administered so that the medicament substance still contained in the pellet is prematurely released through the preforations, contrary to the desired continuity and delay in substance emission so that for a portion of the predetermined period of time, the medicament substance level in the blood system is below the desired level.
Many attempts have been undertaken in the pharmaceutical industry to solve this problem. The material composing the outer coating has been changed, but elimination of the problems of such types of pellets has not been achieved.